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| United States Patent |
5,541,032
|
|
Oftring
, et al.
|
July 30, 1996
|
Electrostatic toners containing phenacyl compounds
Abstract
Electrostatic toners contain a polymeric binder and, as a charge
stabilizer, a compound of the formula
##STR1##
where the ring A may be benzofused and
Het.sym. is the positively charged radical of a heterocycle,
L is C.sub. -C.sub.8 -alkylene,
R is hydrogen, unsubstituted or substituted C.sub.1-C.sub.6 -alkyl,
unsubstituted or substituted phenyl, unsubstituted or substituted hydroxyl
or unsubstituted or substituted amino and
An.crclbar. is one equivalent of an anion.
| Inventors:
|
Oftring; Alfred (Bad Durkheim, DE);
Burkhart; Bernd (Mutterstadt, DE);
Wehlage; Thomas (Hamburg, DE);
Dyllick-Brenzinger; Rainer (Weinheim, DE);
Beck; Karin H. (Ludwigshafen, DE)
|
| Assignee:
|
BASF Aktiengesellschaft (Ludwigshafen, DE)
|
| Appl. No.:
|
432064 |
| Filed:
|
May 1, 1995 |
Foreign Application Priority Data
| May 07, 1994[DE] | 44 16 265.0 |
| Current U.S. Class: |
430/108.11; 430/108.2; 430/108.21 |
| Intern'l Class: |
G03G 009/097 |
| Field of Search: |
430/110
|
References Cited
U.S. Patent Documents
| 4265990 | May., 1981 | Stolka et al. | 430/59.
|
| 5102765 | Apr., 1992 | McCabe et al. | 430/110.
|
| 5147749 | Sep., 1992 | Alexandrovich et al. | 430/110.
|
| Foreign Patent Documents |
| 0382285 | Aug., 1990 | EP.
| |
| 166359 | Jul., 1987 | JP | 430/110.
|
| 93/02397 | Feb., 1993 | WO.
| |
| 93/02400 | Feb., 1993 | WO.
| |
| 93/02053 | Feb., 1993 | WO.
| |
| 93/02054 | Feb., 1993 | WO.
| |
Primary Examiner: Martin; Roland
Attorney, Agent or Firm: Oblon, Spivak, McClelland, Maier & Neustadt, P.C.
Claims
We claim:
1. An electrostatic toner containing a polymeric binder and, as a charge
stabilizer, a compound of formula I:
##STR6##
wherein ring A may be benzofused and Het.sym. is the positively charged
radical of a heterocyclic group selected from the group consisting of
pyrazolyl, imidazolyl, pyridyl, quinolyl and isoquinolyl;
L is C.sub.1 -C.sub.8 -alkylene;
R is hydrogen, unsubstituted or substituted C.sub.1 -C.sub.6 -alkyl,
unsubstituted or substituted phenyl, hydroxyl, C.sub.1 -C.sub.4 -alkoxy,
unsubstituted or substituted phenoxy, amino, C.sub.1 -C.sub.4 -mono- or
dialkylamino, unsubstituted or substituted mono- or diphenylamino or
unsubstituted or substituted N-(C.sub.1 -C.sub.4 -alkyl)-N-phenylamino and
An.crclbar. is one equivalent of an anion.
2. The electrostatic toner as claimed in claim 1, wherein said Het.sym. is
a pyridyl group.
3. The electrostatic toner as claimed in claim 1, wherein substituent L is
C.sub.1 -C.sub.4 -alkylene.
4. The electrostatic toner as claimed in claim 1, wherein ring A is not
benzofused and R is hydrogen, C.sub.1 -C.sub.4 - alkyl, C.sub.1 -C.sub.4
-alkoxy or phenyl.
5. The electrostatic toner as claimed in claim 1, wherein said Het.sym. is
a radical of the formula:
##STR7##
wherein X.sup.1, X.sup.2, X.sup.3 and X.sup.4 independently of one another
are each hydrogen or C.sub.1 -C.sub.6 -alkyl and
X.sub.5 is hydrogen, carboxyl, carbamoyl or C.sub.1 -C.sub.4
-alkoxycarbonyl.
6. The electrostatic toner as claimed in claim 5, wherein said group R is a
member selected from the group consisting of carboxymethyl,
2-carboxyethyl, 2- or 3-carboxypropyl, 2- or 4-carboxybutyl,
2-hydroxyethyl, 2- or 3-hydroxypropyl, 2- or 4-hydroxybutyl,
2-methoxyethyl, 2ethoxyethyl, 2-propoxyethyl, 2-isopropoxyethyl,
2-butoxyethyl, 2- or 3-methoxypropyl, 2- or 3-ethoxypropyl, 2- or
3-propoxypropyl, 2- or 3-butoxypropyl, 2- or 4-methoxybutyl, 2- or
4-ethoxybutyl, 2- or 4-propoxybutyl, 2- or 4-butoxybutyl,
methoxycarbonylmethyl, ethoxycarbonylmethyl, 2-methoxycarbonylethyl,
2-ethoxycarbonylethyl, 2- or 3-methoxycarbonylpropyl, 2- or
3-ethoxycarbonylpropyl, 2- or 4-methoxycarbonylbutyl, 2- or
4-ethoxycarbonylbutyl, 2-, 3- or 4-methylphenyl, 2,4-dimethylphenyl, 2-,
3- or 4-methoxyphenyl, 2,4-dimethoxyphenyl, 2-, 3- or 4-hydroxyphenyl,
2,4-dihydroxyphenyl, 2-, 3- or 4-chlorophenyl, 2,4-dichlorophenyl,
methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, sec-butoxy,
phenoxy, 2-, 3- or 4-methylphenoxy, 2,4-dimethylphenoxy, 2-, 3- or
4-methoxyphenoxy, 2,4-dimethoxyphenoxy, 2-, 3- or 4-hydroxyphenoxy,
2,4-dihydroxyphenoxy, 2-, 3- or 4-chlorophenoxy, 2,4-dichlorophenoxy,
mono- or dimethylamino, mono- or diethylamino, mono- or dipropylamino,
mono- or diisopropylamino, mono- or dibutylamino, mono- or diphenylamino,
mono- or bis(4-chlorophenyl)amino or N-methyl-N-phenylamino.
7. An electrostatic toner as claimed in claim 5, wherein substituent
X.sup.5 is methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl,
isopropoxycarbonyl or butoxycarbonyl.
8. An electrostatic toner as claimed in claim 1, wherein anion
An.sup..crclbar. is halide, sulfate, bisulfate, methanesulfonate,
trifluoromethanesulfonate, 2-hydroxyethanesulfonate, tetraphenylborate,
tetrafluoroborate, p-toluenesulfonate, nitrate, perchlorate,
1-hydroxyethane-1,1-diphosphonate, phosphate, hydrogen phosphate,
dihydrogen phosphate, formate, acetate, oxalate, citrate or tartrate.
9. An electrostatic toner as claimed in claim 1, containing from 0.01 to
10% by weight, based on the weight of the toner, of a compound of the
formula I.
10. A method of preparing an electrostatic toner, comprising:
incorporating, in a polymeric binder, the charge stabilizer compound of
claim 1.
Description
The present invention relates to novel electrostatic toners containing a
polymeric binder and, as a charge stabilizer, a compound of the formula I
##STR2##
where the ring A may be benzofused and
Het.sym. is the positively charged radical of a heterocycle which
originates from the pyrazole, imidazole, pyridine, quinoline or
isoquinoline series,
L is C.sub.1 -C.sub.8 -alkylene,
R is hydrogen, unsubstituted or substituted C.sub.1 -C.sub.6 -alkyl,
unsubstituted or substituted phenyl, hydroxyl, C.sub.1 -C.sub.4 -alkoxy,
unsubstituted or substituted phenoxy, amino, C.sub.1 -C.sub.4 -mono- or
dialkylamino, unsubstituted or substituted mono- or diphenylamino or
unsubstituted or substituted N- (C.sub.1 -C.sub.4 -alkyl) -N-phenylamino
and
An.crclbar. is one equivalent of an anion,
and the use of the abovementioned compounds as charge stabilizers in
electrostatic toners.
Latent electrostatic image recordings are developed by inductively
depositing the toner on the electrostatic image. The charge stabilizers
stabilize the electrostatic charge of the toner. This makes the image
stronger and crisper.
The charge stabilizers used must meet a wide range of requirements:
ability to develop the latent electrostatic image to give a visible image
of high color intensity
easy distribution in the toner formulation in order to produce an
interference-free, crisp, uniform image
insensitivity to moisture
high heat stability.
WO-A-93/02397, WO-A-93/02400, WO-A-93/02053 and WO-A-93/02054 disclose
electrostatic toners which contain, as charge stabilizers, pyridinium
salts containing ester groups, such as N-(ethoxycarbonylmethyl)pyridinium
tetraphenylborate or N-(2-benzoyloxyethyl)pyridinium tetraphenylborate.
However, it has been found that the prior art charge stabilizers frequently
failed to meet the requirements.
It is an object of the present invention to provide a novel electrostatic
toner which possesses charge stabilizers which have advantageous
performance characteristics.
We have found that this object is achieved by the electrostatic toners
defined at the outset, containing phenacyl derivatives of the formula I as
charge stabilizers.
All alkyl and alkylene groups occurring in the abovementioned formula I may
be either straight-chain or branched.
If substituted alkyl groups occur in the abovementioned formula I, suitable
substituents are, for example, hydroxyl, C.sub.1 -C.sub.4 -alkoxy,
carboxyl or C.sub.1 -C.sub.4 -alkoxycarbonyl. In this case, the alkyl
groups have, as a rule, 1 or 2 substituents.
If substituted phenyl groups occur in the abovementioned formula I,
suitable substituents are, for example, C.sub.1 -C.sub.4 -alkyl, C.sub.1
-C.sub.4 -alkoxy, halogen or hydroxyl. In this case, the phenyl groups
have, as a rule, from 1 to 3 substituents.
Suitable heterocycles Het on which the radical Het.sym. are based originate
from the pyrazole, imidazole, pyridine, quinoline or isoquinoline series.
They include, for example, the following structures:
##STR3##
where X.sup.1, X.sup.2 X.sup.3 and X.sup.4 independently of one another
are each hydrogen or C.sub.1 -C.sub.6 -alkyl and
X.sup.5 is hydrogen, carboxyl, carbamoyl or C.sub.1 -C.sub.4
-alkoxycarbonyl.
R, X.sup.1, X.sup.2, X.sup.3 and X.sup.4 are, for example, methyl, ethyl,
propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl,
isopentyl, neopentyl, tert-pentyl, hexyl or 2-methylpentyl.
R may furthermore be, for example, carboxymethyl, 2-carboxyethyl, 2- or
3-carboxypropyl, 2- or 4-carboxybutyl, 2-hydroxyethyl, 2-or
3-hydroxypropyl, 2- or 4-hydroxybutyl, 2-methoxyethyl, 2-ethoxyethyl,
2-propoxyethyl, 2-isopropoxyethyl, 2-butoxyethyl, 2-or 3-methoxypropyl, 2-
or 3-ethoxypropyl, 2- or 3-propoxypropyl, 2- or 3-butoxypropyl, 2- or
4-methoxybutyl, 2- or 4-ethoxybutyl, 2- or 4-propoxybutyl, 2- or
4-butoxybutyl, methoxycarbonylmethyl, ethoxycarbonylmethyl,
2-methoxycarbonylethyl, 2-ethoxycarbonyl-ethyl, 2- or
3-methoxycarbonylpropyl, 2- or 3-ethoxycarbonyl-propyl, 2- or
4-methoxycarbonylbutyl, 2- or 4-ethoxycarbonyl-butyl, 2-, 3- or
4-methylphenyl, 2,4-dimethylphenyl, 2-, 3- or 4-methoxyphenyl,
2,4-dimethoxyphenyl, 2-, 3- or 4-hydroxyphenyl, 2,4-dihydroxyphenyl, 2-,
3- or 4-chlorophenyl, 2,4-dichlorophenyl methoxy, ethoxy, propoxy,
isopropoxy, butoxy, isobutoxy, sec-butoxy, phenoxy, 2-, 3- or
4-methylphenoxy, 2,4-dimethylphenoxy, 2-, 3- or 4-methoxyphenoxy,
2,4-dimethoxyphenoxy, 2-, 3- or 4-hydroxyphenoxy, 2,4-dihydroxyphenoxy,
2-, 3-or 4-chlorophenoxy, 2,4-dichlorophenoxy, mono- or dimethylamino,
mono- or diethylamino, mono- or dipropylamino, mono- or diisopropylamino,
mono- or dibutylamino, mono- or diphenylamino, mono- or
bis(4-chlorophenyl)amino or N-methyl-N-phenylamino. X.sup.5 may
furthermore be, for example, methoxycarbonyl, ethoxycarbonyl,
propoxycarbonyl, isopropoxycarbonyl or butoxycarbonyl.
L is, for example, CH.sub.2, (CH.sub.2).sub.2, (CH.sub.2).sub.3,
(CH.sub.2).sub.4, (CH.sub.2).sub.5, (CH.sub.2).sub.6, (CH.sub.2).sub.7,
(CH.sub.2).sub.8, CH(CH.sub.3)CH.sub.2 or CH(CH.sub.3)CH(CH.sub.3).
Suitable anions on which one equivalent of an anion (An.crclbar.) is based
are, for example, inorganic or organic anions, such as halide, for example
fluorine, chloride, bromide or iodide, sulfate, bisulfate,
methanesulfonate, trifluoromethanesulfonate, 2-hydroxyethanesulfonate,
tetraphenylborate, tetrafluoroborate, p-toluenesulfonate, nitrate,
perchlorate, 1-hydroxyethane-1,1-diphosphonate, phosphate, hydrogen
phosphate, dihydrogen phosphate, formate, acetate, oxalate, citrate or
tartrate.
An anion which may be mentioned in particular is tetrafluoroborate.
Electrostatic toners containing a compound of the formula I where Het.sym.
is derived from a heterocycle from the pyridine series, in particular from
a pyridine of the formula IIc, are preferred.
Electrostatic toners containing a compound of the formula I where L is
C.sub.1 -C.sub.6 -alkylene, in particular C.sub.1 -C.sub.2 -alkylene, are
also preferred.
Electrostatic toners containing a compound of the formula I where the ring
A is not benzofused and R is hydrogen, C.sub.1 -C.sub.4 -alkyl, C.sub.1
-C.sub.4 -alkoxy or phenyl are furthermore preferred.
Particular important electrostatic toners are those containing a compound
of the formula I where Het.sym. is a radical of the formula IIf.
##STR4##
where Z is hydrogen, methyl, carboxyl or C.sub.1 -C.sub.4 -alkoxycarbonyl,
especially hydrogen.
The phenacyl compounds of the formula I are as a rule compounds which are
known or which can be obtained by methods known per se.
For example, a ketone of the formula III
##STR5##
where Hal is halogen, preferably chlorine or bromine, and L, R and the
ring A each have the abovementioned meanings, can be reacted with a
heterocycle of the formula IV
Het (IV),
where Het has the abovementioned meanings. A compound of the formula I
where An.crclbar. is halide is obtained in this manner.
The reaction of the components III and IV is advantageously carried out in
an inert solvent, such as toluene, xylene, petroleum ether, naphtha,
cyclohexane, acetone, tetrahydrofuran, dioxane, methanol, ethanol,
isopropanol, methyl or ethyl acetate or acetonitrile. As a rule, the
reaction is carried out at from 40.degree. to 130.degree. C., preferably
from 60.degree. to 100.degree. C., and under atmospheric pressure.
By subjecting these compounds to double decomposition with salts of the
formula V
M.sym. An.crclbar. (V),
where M.sym. is one equivalent of a metal ion, in particular an alkali
metal ion, and An.crclbar. has the abovementioned meanings (with the
exception of halide), in an aqueous medium, it is possible to obtain, for
example, those compounds of the formula I in which An.crclbar. differs
from halide. Further details are also given in the examples.
The amount of the compounds of the formula I in the electrostatic toner is,
as a rule, from 0.01 to 10% by weight, based on the weight of the toner.
The polymeric binders present in the novel electrostatic toners are known
per se. They are as a rule thermoplastic and have a softening point of
from 40.degree. to 200.degree. C., preferably from 50.degree. to
130.degree. C., in particular from 65.degree. to 115.degree. C. Examples
of polymeric binders are polystyrene, copolymers of styrene with an
acrylate or methacrylate, copolymers of styrene with butadiene and/or
acrylonitrile, polyacrylates, polymethacrylates, copolymers of an acrylate
or methacrylate with vinyl chloride or vinyl acetate, polyvinyl chloride,
copolymers of vinyl chloride with vinylidene chloride, copolymers of vinyl
chloride with vinyl acetate, polyester resins, epoxy resins, polyamides or
polyurethanes.
In addition to the abovementioned compounds of the formula I and the
polymeric binders, the novel toners may contain known amounts of
colorants, magnetic material, waxes and fluxes.
The colorants may be organic dyes or pigments, such as nigrosine, aniline
blue, 2,9-dimethylquinacridone, C.I. Disperse Red 15 (C.I. 6010), C.I.
Solvent Red 19 (C.I. 26 050), C.I. Pigment Blue 15 (C.I. 74 160), C.I.
Pigment Blue 22 (C.I. 69 810) or C.I. Solvent Yellow 16 (C.I. 12 700), or
inorganic pigments, such as carbon black, red lead, yellow lead oxide or
chrome yellow. In general, the amount of the colorant present in the toner
does not exceed 15% by weight, based on the weight of the toner.
The magnetic material may be, for example, iron, nickel, chromium oxide,
iron oxide or a ferrite of the formula MeFe.sub.2 O.sub.4, where Me is a
divalent metal, eg. iron, cobalt, zinc, nickel or manganese.
The novel toners are prepared by conventional processes, for example by
mixing the components in a kneader and then powdering the mixture or by
melting the polymeric binder or a mixture of the polymeric binders, then
finely dispersing one or more compounds of the formula I and the other
additives, if used, in the molten resin using the mixing and kneading
apparatuses known for this purpose, then cooling the melt to give a solid
material and finally milling the solid material to give particles of the
desired size (as a rule from 0.1 to 50 .mu.m). It is also possible to
dissolve the polymeric binder and the charge stabilizer in a common
solvent and to add the other additives to the solution. The solution can
therefore be used as a liquid toner.
However, the liquid may also be spray-dried in a manner known per se, the
solvents can be evaporated off or the liquid can be freeze-dried and the
solid residue milled to give particles of the desired size.
It is also possible for the compounds of the formula I which are used as
charge stabilizers to be finely dispersed in the solution of the polymeric
binder instead of dissolving them. The resulting toner formulation can
then be used, for example according to U. S. Pat. No. 4,265,990, in a
xerographic image recording system.
The abovementioned compounds of the formula I are advantageous charge
stabilizers. As a rule, they have the performance characteristics required
at the outset and in particular, when added to a toner preparation, impart
to the latter an advantageous electrostatic charging profile, ie. the
toners can be rapidly charged to a high charge. The charge stabilizers to
be used according to the invention furthermore ensure that the charge is
kept constant at a high level.
The examples which follow illustrate the invention.
A) Preparation of the phenacyl compounds
EXAMPLE H1
Preparation of 4-methylphenacylpyridinium bromide
64 g (0.3 mol) of 4-methylphenacyl bromide in 80 ml acetone were initially
taken and heated to 60.degree. C. 24 g (0.3 mol) of pyridine were then
slowly added dropwise. The reaction mixture was stirred for a further hour
at 60.degree. C. and cooled to room temperature. The precipitated solid
was filtered off and washed with acetone. After drying, 82.5 g
(corresponding to a yield of 94%) of the title compound were obtained in
the form of a yellow powder. The purity of the product was more than 99%.
EXAMPLE H2
Preparation of 4-methylphenacylpyridinium tetrafluoroborate
30 g (0.1 mol) of 4-methylphenacylpyridinium bromide in 120 ml of water
were initially taken and heated to 60.degree. C. 11 g (0.1 mol) of sodium
tetrafluoroborate were then added and the mixture was slowly cooled to
room temperature. It was stirred for a further hour at room temperature,
and the precipitated product was filtered off and washed with water. After
drying, 22.2 g (corresponding to a yield of 74%) of the title compound
were obtained in the form of a yellow solid. The purity of the product was
more than 99%.
EXAMPLE H3
Preparation of 4-methylphenacylpyridinium tetraphenylborate
The title compound was prepared similarly to Example 2 from
4-methylphenacylpyridinium bromide and sodium tetraphenylborate in a yield
of 100%.
EXAMPLE H4
Preparation of 4-methoxyphenacylpyridinium bromide
The title compound was prepared similarly to Example 1 from
4-methoxyphenacyl bromide and pyridine in a yield of 97%.
EXAMPLE H5
Preparation of 4-methoxyphenacylpyridinium tetrafluoroborate
The title compound was prepared similarly to Example 2 from
4-methoxyphenacylpyridinium bromide and sodium tetrafluoroborate in a
yield of 85%.
EXAMPLE H6
Preparation of 4-methoxyphenacylpyridinium tetraphenylborate
The title compound was prepared similarly to Example 2 from
4-methoxyphenacylpyridinium bromide and sodium tetraphenylborate in a
yield of 100%.
EXAMPLE H7
Preparation of 3-methoxyphenacylpyridinium chloride
The title compound was prepared similarly to Example 1 from
3-methoxyphenacyl chloride and pyridine in a yield of 93%.
EXAMPLE H8
Preparation of naphthacylpyridinium bromide
The title compound was prepared similarly to Example 1 from
.omega.-bromo-2-acetonaphthone and pyridine in a yield of 96%.
EXAMPLE H9
Preparation of 4-tert-butylphenacylpyridinium chloride
The title compound was prepared similarly to Example 1 from
4-tert-butylphenacyl chloride and pyridine in a yield of 94%.
EXAMPLE H10
Preparation of 4-isopropylphenacylpyridinium chloride
The title compound was prepared similarly to Example 1 from
4-isopropylphenacyl chloride and pyridine in a yield of 93%.
EXAMPLE H11
Preparation of 4-phenylphenacylpyridinium bromide
The title compound was prepared similarly to Example 1 from
4-phenylphenacyl bromide and pyridine in a yield of 95%.
B) Use
The use examples were carried out using colorant-free toner models
consisting of resin and the novel charge stabilizers.
I. Preparation of the toners
EXAMPLE A1
0.2 g of the compound from Example H1 was introduced into a solution of 10
g of a uncrosslinked styrene/butyl acrylate resin in 100 ml of p-xylene at
room temperature and the mixture was then freeze-dried and milled. Toner
particles having a mean particle size of 50 .mu.m were obtained by
classification.
EXAMPLE A2
10 g of a uncrosslinked styrene/butyl acrylate resin and 0.2 g of the
compound from Example H1 were thoroughly mixed in a mixer, kneaded at
120.degree. C., extruded and milled. Toner particles having a mean
particle size of 50 .mu.m were obtained by classification.
EXAMPLE A3
0.2 g of the compound from Example H2 was introduced into a solution of 10
g of a linear polyester resin in 100 ml of p-xylene at room temperature
and the mixture was then freeze-dried and milled. Toner particles having a
mean particle size of 50 .mu.m were obtained by classification.
EXAMPLE A4
10 g of a linear, uncrosslinked polyester resin and 0.2 g of the compound
from Example H2 were thoroughly mixed in a mixer, kneaded at 120.degree.
C., extruded and milled. Toner particles having a mean particle size of 50
.mu.m were obtained by classification.
EXAMPLE A5
10 g of a linear, uncrosslinked polyester resin and 0.2 g of the compound
from Example H3 were thoroughly mixed in a mixer, kneaded at 120.degree.
C., extruded and milled. Toner particles having a mean particle size of 50
.mu.m were obtained by classification.
EXAMPLE A6
0.2 g of the compound from Example H5 was introduced into a solution of 10
g of a linear polyester resin in 100 ml of p-xylene at room temperature
and the mixture was then freeze-dried and milled. Toner particles having a
mean particle size of 50 .mu.m were obtained by classification.
EXAMPLE A7
10 g of a linear, uncrosslinked polyester resin and 0.2 g of the compound
from Example H5 were thoroughly mixed in a mixer, kneaded at 120.degree.
C., extruded and milled. Toner particles having a mean particle size of 50
.mu.m were obtained by classification.
EXAMPLE A8
10 g of a linear, uncrosslinked polyester resin and 0.2 g of the compound
from Example H6 were thoroughly mixed in a mixer, kneaded at 120.degree.
C., extruded and milled. Toner particles having a mean particle size of 50
.mu.m were obtained by classification.
EXAMPLE A9
0.2 g of the compound from Example H7 was introduced into a solution of 10
g of an uncrosslinked styrene/butyl acrylate resin in 100 ml of p-xylene
at room temperature and the mixture was then freeze-dried and milled.
Toner particles having a mean particle size of 50 .mu.m were obtained by
classification.
EXAMPLE A10
0.2 g of the compound from Example H8 was introduced into a solution of 10
g of an uncrosslinked styrene/butyl acrylate resin in 100 ml of p-xylene
at room temperature and the mixture was then freeze-dried and milled.
Toner particles having a mean particle size of 50 .mu.m were obtained by
classification.
EXAMPLE A11
0.2 g of the compound from Example H9 was introduced into a solution of 10
g of an uncrosslinked styrene/butyl acrylate resin in 100 ml of p-xylene
at room temperature and the mixture was then freeze-dried and milled.
Toner particles having a mean particle size of 50 .mu.m were obtained by
classification.
EXAMPLE A12
0.2 g of the compound from Example H10 was introduced into a solution of 10
g of an uncrosslinked styrene/butyl acrylate resin in 100 ml of p-xylene
at room temperature and the mixture was then freeze-dried and milled.
Toner particles having a mean particle size of 50 .mu.m were obtained by
classification.
EXAMPLE A13
0.2 g of the compound from Example H11 was introduced into a solution of 10
g of an uncrosslinked styrene/butyl acrylate resin in 100 ml of p-xylene
at room temperature and the mixture was then freeze-dried and milled.
Toner particles having a mean particle size of 50 .mu.m were obtained by
classification.
II. Preparation of the developers and testing
For the preparation of a developer, 99% by weight of a steel carrier which
had a mean particle size of 100 .mu.m and 1% by weight of the toner were
accurately weighed in and were activated on a roller stand for a period
defined below. The electrostatic charge build-up on the developer was then
determined. In a commercial q/m meter (from Epping GmbH, Neufahrn), about
5 g of the activated developer were introduced into a hard-blow-off cell
electrically connected to an electrometer. The mesh size of the sieves
used in the measuring cell were 63 .mu.m.
This ensured that the toner was blown off as completely as possible but the
carrier remained in the measuring cell. By means of a strong air current
(about 4,000 cm.sup.3 /min) and simultaneous suction, the toner was
virtually completely removed from the carrier particles, the latter
remaining in the measuring cell. The charge build-up on the carrier was
recorded on the electrometer. It corresponded to the magnitude of the
charge build-up on the toner particles, but with the opposite sign. The
magnitude of q with the opposite sign was therefore used for calculating
the q/m value. By reweighing the measuring cell, the mass of blown-off
toner was determined and the electrostatic charge build-up q/m was
calculated from this.
The charge build-up determined for the toners is summarized in the table
below.
TABLE
______________________________________
Charge build-up after
Compound Prepara- activation for
Example
from tion of 10 min 30 60 120
No. Example the toner*
[.mu.C/g]
min min min
______________________________________
A1 H1 F 6.8 5.5 5.1 4.2
A2 H1 K 4.2 2.9 2.6 2.8
A3 H2 F 20.6 22.7 24.7 24.0
A4 H2 K 7.5 7.1 7.6 7.6
A5 H3 K 11.6 13.6 12.9 12.1
A6 H5 F 24.5 24.3 25.7 24.7
A7 H5 K 10.5 11.2 10.5 11.5
A8 H6 K 13.7 13.7 13.6 1.6
A9 H7 F 9.3 7.0 6.6 6.2
A10 H8 F 6.7 5.1 4.4 3.8
A11 H9 F 1.8 1.7 1.5 1.4
A12 H10 F 1.9 2.2 1.8 1.8
A13 H11 F 6.7 4.6 3.1 2.2
______________________________________
*The toner was prepared either by freezedrying according to Example A1
(denoted by F in the table) or by kneading at above the softening point o
the resin according to Example A2 (denoted by K in the table).
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